US4911444A - Tennis racket - Google Patents

Tennis racket Download PDF

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Publication number
US4911444A
US4911444A US07/164,394 US16439488A US4911444A US 4911444 A US4911444 A US 4911444A US 16439488 A US16439488 A US 16439488A US 4911444 A US4911444 A US 4911444A
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US
United States
Prior art keywords
frame
thickness
strung surface
maximum
tennis racket
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/164,394
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English (en)
Inventor
Minoru Yoneyama
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Yonex KK
Original Assignee
Yonex KK
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Filing date
Publication date
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Assigned to YONEX KABUSHIKI KAISHA reassignment YONEX KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: YONEYAMA, MINORU
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    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B49/10—Frames made of non-metallic materials, other than wood
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B2049/0211—Frames with variable thickness of the head in a direction perpendicular to the string plane

Definitions

  • the present invention relates to a tennis racket of a type in which frame and handle shaft are integrally made of fiber reinforced plastics (hereinafter referred to as "FRP") and the frame is strung with some strings such as a gut.
  • FRP fiber reinforced plastics
  • Japanese Utility Model Application No. 58-188069 shows another example of improved racket whose frame is added with weight by protruding a part of the internal circumferential surface of the frame radially inwards toward the center of strung surface.
  • this racket also causes several problems owing to its frame shape.
  • Such protruded section increases an air resistance and generates turbulent flow which is not ignored, so that energy loss is increased during swing and user may feel unpleasant.
  • Another object of the present invention is to provide a tennis racket which can effectively transmit an energy to a ball and can provide a good swing feeling.
  • Still another object of the present invention is to provide a tennis racket improved in its mechanical strength and durability.
  • a further object of the present invention is to provide a tennis racket which can be manufactured in a simple work.
  • a tennis racket includes a frame for defining a strung surface and a shaft, these frame and shaft being integrally formed of fiber reinforced plastic material.
  • a first thickness of the frame in a direction of plane containing the strung surface is substantially uniform around the circumference of the frame, while a second thickness of the frame in a direction perpendicular to the strung surface is gradually varied.
  • the second thickness is maximum at side sections of said frame interposing a sweet spot in the strung surface and is minimum at the top and bottom portions of the frame in such a manner that the maximum thickness is thicker in the range from 35% to 60% than the minimum thickness, whereby a weight per unit length of the frame increases toward the side sections.
  • the weight is increased at the side sections of the frame without any protrusion to the strung surface. Therefore, twisting movement of the racket can be effectively reduced while maintaining an air resistance to the racket during a swing motion in the same level as conventional tennis rackets.
  • the increase in thickness of the frame in a direction perpendicular to the strung surface contributes to a stabilization of the swing.
  • the side sections are located at portions slightly below a level of the geometric center of the strung surface.
  • the frame may have a cross section of a substantially oval shape of which minor axis extends in a direction of the first thickness and a longitudinal axis thereof extends in a direction of the second thickness.
  • FIG. 1 is an elevational view showing a tennis racket according to an embodiment of the present invention
  • FIG. 2 is a side view showing the tennis racket of FIG. 1;
  • FIG. 3 is a cross sectional view taken along the line III--III in FIG. 1;
  • FIG. 4 is a cross sectional view taken along the line IV--IV in FIG. 1.
  • FIG. 1 shows one preferred embodiment of a tennis racket generally indicated by numeral 10 according to the present invention, which includes a frame 12, a handle or grip 14 defining the lower end of the racket, and a shaft 16 extending between the frame 12 and grip 14.
  • the shaft 16 bifurcates above the grip 14 to define a substantially inverted triangular hollow space 26 therebetween and between the bottom portion 12c of the frame 12.
  • the area defined within the frame 12 is adapted to be strung with strings such as guts (not shown) in its vertical and horizontal directions so a to form a ball hitting face.
  • the frame 12 and the shaft 16 are integrally formed by covering a core 22 (see FIGS.
  • the frame 12 contains a groove 18 in its outer peripheral surface and a plurality of through holes 20 formed in the groove 18. The through holes 20 are used for stringing the gut.
  • the cross section of the frame 12 is substantially formed in an oval shape whose minor axis extends in a plane of the strung surface and longitudinal axis extends in a plane perpendicular to the strung surface.
  • the thickness "t" of the frame 12 along the minor axis is substantially uniform around the circumference of the frame 12 except for the junctions between the shaft 16 and the frame 12 at which the thickness "t" is somewhat increased as shown in FIG. 1.
  • the thickness "T" of the frame 12 along the longitudinal axis is not uniform and is gradually varied around the circumference of the frame 12.
  • the thickness "T” becomes maximum at both side sections 12a-12a which interposes a sweet spot located slightly below the geometric center C of the frame 12, and becomes minimum at the top portion 12b and bottom portion 12c, these maximum and minimum thicknesses being indicated in FIG. 2 as “T1" and “T2" respectively.
  • the thickness “T” is gradually increased from the top portion 12b and bottom portion 12c to the side sections 12a.
  • FIGS. 3 and 4 which show cross sections at 12b and 12a, respectively, the wall thickness of the core 22 and the FRP layers 24 is substantially uniform around the frame 12. Therefore, a weight per unit length of the frame 12 is maximum at the side sections 12a having the thickness "T1"and gradually decreases toward the top and bottom portions 12b and 12c to become minimum at the "T2" thickness portions.
  • the maximum thickness "T1" is set to 30 mm and the minimum thickness “T2" is 21 mm.
  • the maximum thickness "T1” is increased about 43% than the minimum thickness "T". This increasing ratio can be obtained from the following formula:
  • the increasing ratio can be selected from 35 to 60%. If it is less than 35%, the side sections 12a can not satisfy the weight increment to increase moment of inertia. On the contrary, if the increasing ratio is larger than 60%, center of gravity of the racket will excessively be shifted downwards and thus its weight balance will be lost.
  • the side sections 12a having the maximum thickness should be so located as to interpose the sweet spot in the strung surface, the sweet spot usually being near the geometric center C or slightly therebelow.
  • the increase in unit weight of the frame toward the side sections thereof achieves the same effect as by adding weight members to the side sections, whereby moment of inertia of the frame is increased to reduce twisting movement of the racket. Further, this advantage can be obtained without providing any protrusion on the inner peripheral surface of the frame and therefore without increasing air resistance during swing motion.
  • the frame thickness is increased only in the direction perpendicular to the strung surface, i.e. in the direction of swing motion, which can ensure a smooth and stable swing of the racket. This will be appreciated by, for example, thinking of swinging a hollow cylindrical member in its axial direction and in an other directions.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Laminated Bodies (AREA)
US07/164,394 1987-11-17 1988-03-04 Tennis racket Expired - Fee Related US4911444A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1987189359U JPH0429624Y2 (de) 1987-11-17 1987-11-17
JP62-189359[U] 1987-11-17

Publications (1)

Publication Number Publication Date
US4911444A true US4911444A (en) 1990-03-27

Family

ID=16240004

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/164,394 Expired - Fee Related US4911444A (en) 1987-11-17 1988-03-04 Tennis racket

Country Status (7)

Country Link
US (1) US4911444A (de)
JP (1) JPH0429624Y2 (de)
AU (1) AU598892B2 (de)
CA (1) CA1299602C (de)
DE (1) DE3800362A1 (de)
FR (1) FR2623097A1 (de)
GB (2) GB8800344D0 (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5048830A (en) * 1990-09-20 1991-09-17 Lo Kun Nan Racket frame with shock absorbing characteristics
US5062634A (en) * 1990-08-31 1991-11-05 Wilson Sporting Goods Co. Squash racket
US5110125A (en) * 1988-04-26 1992-05-05 Skis Rossignol S. A. Sport racket
US5183265A (en) * 1989-09-11 1993-02-02 Head Sportgerate Gesellschaft M.B.H. & Co. Ohg Racquets, in particular tennis racquets
US5299801A (en) * 1991-05-23 1994-04-05 Donnay International S.A. Tennis racket
US5312102A (en) * 1993-02-04 1994-05-17 Lisco, Inc. Variable inertia head racket
US5540434A (en) * 1990-08-21 1996-07-30 Wilson Sporting Goods Co. Tennis racket
US6062994A (en) * 1998-04-10 2000-05-16 Ef Composite Technologies, L.P. Reinforced racquet with flat string bed
US6422958B1 (en) 1994-02-24 2002-07-23 David W. Repetto Frame for a game racquet formed by filament winding
US6447412B1 (en) 2000-04-18 2002-09-10 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
GB2404869A (en) * 2003-08-15 2005-02-16 Imp College Innovations Ltd Tennis racket dimensioned to reduce ball spin
KR200450692Y1 (ko) 2008-10-08 2010-10-22 (주)스포츠유피 스트링의 탄성력을 강화한 배드민턴 라켓 프레임

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2258158A (en) * 1991-08-02 1993-02-03 Kuni Tseng Seamless racket.
CN1047323C (zh) * 1993-08-05 1999-12-15 肯·德高里斯 运动球拍的配重平衡系统
DE4495737T1 (de) * 1993-08-05 1996-10-17 Degaris Ultradünner Schlägerrahmen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3647211A (en) * 1970-06-08 1972-03-07 James H Doessel Plastic tennis racket having predetermined cross sections effecting flexibility
US4177990A (en) * 1976-10-04 1979-12-11 Nippon Gakki Seizo Kabushiki Kaisha Racket frame
US4561655A (en) * 1984-06-14 1985-12-31 Ektelon Tubular steel racquet frame having varying cross-section
US4664380A (en) * 1984-09-22 1987-05-12 Siegfried Kuebler Racket having thickened shaft portion

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878020A (en) * 1949-12-16 1959-03-17 Roy H Robinson Racket for batting games
JPS52146329A (en) * 1976-05-27 1977-12-06 Nippon Gakki Seizo Kk Racket frame
JPS53103489A (en) * 1977-02-22 1978-09-08 V Nauchinooisusuredobuaterusuk N*n*nntrimethyl derivative of polyene amphoteric biotics
JPS5412930A (en) * 1977-06-30 1979-01-31 Hitachi Chem Co Ltd Racket frame
WO1980002510A1 (en) * 1979-05-17 1980-11-27 J Frolow Tennis racket
EP0171500A3 (en) * 1984-07-31 1987-09-30 Consolidated Sporting Goods Pty. Limited Racquet frame with tapered thickness

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3647211A (en) * 1970-06-08 1972-03-07 James H Doessel Plastic tennis racket having predetermined cross sections effecting flexibility
US4177990A (en) * 1976-10-04 1979-12-11 Nippon Gakki Seizo Kabushiki Kaisha Racket frame
US4561655A (en) * 1984-06-14 1985-12-31 Ektelon Tubular steel racquet frame having varying cross-section
US4664380A (en) * 1984-09-22 1987-05-12 Siegfried Kuebler Racket having thickened shaft portion

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5110125A (en) * 1988-04-26 1992-05-05 Skis Rossignol S. A. Sport racket
US5183265A (en) * 1989-09-11 1993-02-02 Head Sportgerate Gesellschaft M.B.H. & Co. Ohg Racquets, in particular tennis racquets
US5540434A (en) * 1990-08-21 1996-07-30 Wilson Sporting Goods Co. Tennis racket
US5062634A (en) * 1990-08-31 1991-11-05 Wilson Sporting Goods Co. Squash racket
US5048830A (en) * 1990-09-20 1991-09-17 Lo Kun Nan Racket frame with shock absorbing characteristics
US5299801A (en) * 1991-05-23 1994-04-05 Donnay International S.A. Tennis racket
US5312102A (en) * 1993-02-04 1994-05-17 Lisco, Inc. Variable inertia head racket
US6422958B1 (en) 1994-02-24 2002-07-23 David W. Repetto Frame for a game racquet formed by filament winding
US6062994A (en) * 1998-04-10 2000-05-16 Ef Composite Technologies, L.P. Reinforced racquet with flat string bed
US6447412B1 (en) 2000-04-18 2002-09-10 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
US6958104B1 (en) 2000-04-18 2005-10-25 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
GB2404869A (en) * 2003-08-15 2005-02-16 Imp College Innovations Ltd Tennis racket dimensioned to reduce ball spin
WO2005016462A1 (en) * 2003-08-15 2005-02-24 Imperial College Innovations Limited Tennis racket
KR200450692Y1 (ko) 2008-10-08 2010-10-22 (주)스포츠유피 스트링의 탄성력을 강화한 배드민턴 라켓 프레임

Also Published As

Publication number Publication date
FR2623097A1 (de) 1989-05-19
GB8800344D0 (en) 1988-02-10
JPH0429624Y2 (de) 1992-07-17
JPH0180162U (de) 1989-05-30
DE3800362A1 (de) 1989-05-24
CA1299602C (en) 1992-04-28
AU8317287A (en) 1989-05-18
GB2212403A (en) 1989-07-26
AU598892B2 (en) 1990-07-05
GB8801181D0 (en) 1988-02-17

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Legal Events

Date Code Title Description
AS Assignment

Owner name: YONEX KABUSHIKI KAISHA, 900-1, TSUKANOYAMA, OAZA,

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:YONEYAMA, MINORU;REEL/FRAME:004865/0177

Effective date: 19880128

Owner name: YONEX KABUSHIKI KAISHA,JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:YONEYAMA, MINORU;REEL/FRAME:004865/0177

Effective date: 19880128

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Expired due to failure to pay maintenance fee

Effective date: 19940330

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362